Folded Li/MnO2 Cell Layout for High-Current Discharge Efficiency
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Solution Overview
Problem
Primary electrochemical cells and batteries face limitations in discharge efficiency, particularly at high load conditions due to high internal resistance, which restricts their ability to deliver stored energy effectively, especially in modern electronic devices that require high power and fast charging.
Innovation Solution
A high energy Li/MnO2 cell design with multiple thin strip electrodes over-folding into segments, maintaining a low capacity-to-active area ratio and reduced internal resistance, allowing for efficient high-drain performance, achieved through a folded jellyroll configuration with thin cathode and anode strips and strategically placed separators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If primary electrochemical cells are designed for high specific energy, then they can store more energy, but their internal resistance increases and discharge efficiency deteriorates under high load conditions
Solution Approach 1:
The electrodes are divided into multiple thin strips instead of using single thick electrodes. This segmentation increases the total surface area for electrochemical reactions while maintaining low internal resistance, enabling both high energy storage and efficient discharge at high rates
Solution Approach 2:
The patent transitions from conventional planar electrode arrangements to a three-dimensional folded jellyroll configuration. This dimensional change maximizes the electrode surface area within a compact volume, increasing active reaction sites while maintaining short ion transport paths that reduce internal resistance
2Reliability
If the interfacial surface area between electrodes is increased to improve current density, then discharge efficiency improves, but the cell complexity and manufacturing difficulty increase
Solution Approach 1:
Multiple electrode strips are folded and stacked together to form a compact jellyroll structure. This merging approach achieves high interfacial surface area without requiring complex individual electrode geometries, simplifying manufacturing while maximizing discharge efficiency
Solution Approach 2:
The thin electrode strips are nested within each other in a folded configuration, with separators and electrolyte impregnated between them. This nested structure maximizes surface area contact while maintaining a compact, manufacturable form factor
3Reliability
If thin electrode strips are used to reduce internal resistance, then discharge efficiency at high rates improves, but the mechanical strength and structural stability of the cell may deteriorate
Solution Approach 1:
The cell employs a composite structure combining thin electrode strips with separator layers and electrolyte-impregnated materials. This composite construction provides mechanical reinforcement to the thin electrodes while maintaining their low resistance characteristics, achieving both high discharge efficiency and structural stability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design significantly enhances discharge efficiency, enabling the cell to deliver a high percentage of its stored energy at high power demand, outperforming conventional cells in terms of energy delivery and capacity utilization, especially at high current rates and temperatures.
Implementation Method 1
an anode, a cathode, and at least two separators, the anode, the cathode and the separators are longitudinally stacked to form an electrodes set
Data Source
AI summary
Provided herein is an electrochemical cell designed for high current discharge, which includes a cathode strip, an anode strip, and at least two separator strips, being longitudinally stacked to form an electrodes set that is folded into at least four segments and designed to exhibit a ratio of its nominal capacity per its active area lower than 12 mAh/cm2, such that the cell is characterized by a discharge efficiency at room temperature of at least 30% to a cut-off voltage of ⅔ of its original voltage at a discharge current of 1,250 m A. Also provided are process of manufacturing, and uses of the cell, which is particularly useful in high drain-rate applications as charging a cellular phone.